A. Technical Field
The present invention relates to a cement dispersant, a method for producing a polycarboxylic acid for a cement dispersant and a cement composition. More specifically, it relates to a cement dispersant synthesized by using a polyalkylene glycol ester type monomer or a polyalkylene glycol ether type monomer, having alkylene oxide obtained by the addition reaction in a specific temperature range, and a cement dispersant which can achieve high percentage in water reduction, a method for producing a polycarboxylic acid for such a cement dispersant and a cement composition.
B. Background Art
In recent concrete fields, improvement in durability and strength of concrete structures is strongly demanded. Reduction in unit water amount is an important subject, and development of high performance AE water reducing agents is energetically conducted in each cement admixture maker. Of those, polycarboxylic acid type high performance AE water reducing agents have the excellent characteristic which exhibits extremely high water reducing property which cannot be achieved by other high performance AE water reducing agents such as naphthalene type. However, the water reducing performance is not still sufficient.
A. Objects of the Invention
An object of the present invention is to provide a cement dispersant which improves water reducing performance, a method for producing a cement dispersant and a cement composition.
B. Disclosure of the Invention
The present inventors have found that a polycarboxylic acid for a cement dispersion, obtained by a specific production method is an excellent cement dispersion exhibiting high water reducing performance, and have completed the present invention. That is, the present invention is to provide a cement dispersant exhibiting high to water reducing performance, a method for producing a polycarboxylic acid for a cement dispersant and a cement composition.
The above various objects are achieved by
(1) a cement dispersant containing a polycarboxylic acid having a polyalkylene glycol at a side chain, wherein the polyalkylene glycol is obtained by adding alkylene oxide in a range of 80 to 155xc2x0 C.
The present invention is also achieved by
(2) a cement dispersant comprising a polycarboxylic acid having a polyalkylene glycol at a side chain, wherein the polycarboxylic acid comprises a polyalkylene glycol type monomer unit having a polyalkylene glycol at a side chain and a carboxylic acid type monomer unit, characterized in that, as a polyalkylene glycol type monomer giving the polyalkylene glycol type monomer unit, a polyalkylene glycol type monomer having a molecular weight distribution which has a main peak, belt has no second peak on the higher molecular weight side of the main peak, or has a second peak on the higher molecular weight side of the main peak in an area ratio of 8% or less based on the total area of the main peak and the second peak.
The present invention is also achieved by
(3) a method for producing a polycarboxylic acid for a cement dispersant, having a polyalkylene glycol at a side chain, characterized by adding alkylene oxide to an active hydrogen-containing compound in a range of 80 to 155xc2x0 C.
Further, the present invention is achieved by
(4) a method for producing a polycarboxylic acid for a cement dispersant comprising, as repeating units, a polyalkylene glycol ether type unit (I) represented by the general formula (1) 
(where, R1 to R3 each independently represent hydrogen or methyl group, R5O represents one kind or a mixture of two or more kinds of oxyalkylene group having 2 to 4 carbon atoms, in the case of two or more kinds, those may be added in a block state or random state, R6 represents hydrogen, alkyl group having 1 to 22 carbon atoms, phenyl group, or alkyl phenyl group (the alkyl group in the alkyl phenyl group having 1 to 22 carbon atoms), R4 represents xe2x80x94CH2xe2x80x94, xe2x80x94(CH2)2xe2x80x94 or xe2x80x94C(CH3)2xe2x80x94, and p represents an integer of 1 to 300), and a dicarboxylic acid type unit (II) represented by the general formula (2) 
(where, M1 and M2 each independently represent hydrogen, monovalent metal, divalent metal, ammonium or organic amine, X represents xe2x80x94OM2, or xe2x80x94Yxe2x80x94(R7O)rR8, Y represents xe2x80x94Oxe2x80x94, or xe2x80x94NHxe2x80x94, R7O represents one kind or a mixture of two or more kinds of oxyalkylene group having 2 to 4 carbon atoms, in the case of two or more kinds, those may be added in a block state or a random state, R8 represents hydrogen, alkyl group having 1 to 22 carbon atoms, phenyl group, aminoalkyl group, alkyl phenyl group, or hydroxyalkyl group (each alkyl group in the aminoalkyl, alkyl phenyl and hydroxyalkyl groups having 1 to 22 carbon atoms), r is an integer of 0 to 300, and an acid anhydride group (xe2x80x94COxe2x80x94Oxe2x80x94COxe2x80x94) may be formed in place of the xe2x80x94COOM1 and COX groups between carbon atoms to which the xe2x80x94COOM1 and COX groups should be bonded respectively), characterized in that a polyalkylene glycol ether type monomer obtained by addition reaction of alkylene oxide having 2 to 4 carbon atoms in a range of 80 to 155xc2x0 C. with an unsaturated alcohol (B-1) represented by the general formula (3) 
(where, R1 to R3 each independently represent hydrogen, or methyl group, and R4 represents xe2x80x94CH2xe2x80x94, xe2x80x94(CH2)2xe2x80x94, or xe2x80x94C(CH3)2xe2x80x94) is used as a polyalkylene glycol ether type monomer giving the general formula (1) which is the repeating unit.
Furthermore, the present invention is achieved by
(5) a method for producing a polycarboxylic acid for a cement dispersion, wherein the polycarboxylic acid comprises, as repeating units, a polyalkylene glycol ester type unit (III) represented by the general formula (4) 
(where, R9 represents hydrogen, or methyl group, R10O represents one kind or a mixture of two or more kinds of oxyalkylene group having 2 to 4 carbon atoms, in the case of two or more kinds, those may be added in a block state or random state, R11 represents alkyl group having 1 to 22 carbon atoms, phenyl group, or alkyl phenyl group (the alkyl group in the alkyl phenyl group having 1 to 22 carbon atoms), and s is an integer of 1 to 300), and a monocarboxylic acid type unit (IV) represented by the general formula (5) 
(where, R12 represents hydrogen, or methyl group, and M3 represents hydrogen, monovalent metal, divalent metal, ammonium, or organic amine), characterized in that a polyalkylene glycol (6) obtained by addition reaction of alkylene oxide having 2 to 4 carbon atoms with an alcohol (B-2) represented by the general formula (7) in a range of 80 to 155xc2x0 C. is used in producing a polyalkylene glycol ester type monomer giving the repeating unit (III) by esterification between the polyalkylene glycol (6) represented by the general formula (6)and (meth)acrylic acid or ester interchange between the polyalkylene glycol (6) and alkyl(meth)acrylates (the alkyl group in the alkyl(meth)acrylates having 1 to 22 carbon atoms).
HOxe2x80x94(R10O)sxe2x80x94R11xe2x80x83xe2x80x83(6)
(where, R10O represents one kind or a mixture of two or more kinds of oxyalkylene group having 2 to 4 carbon atoms, in the case of two or more, those may be added in a block state or random state, R11 represents alkyl group having 1 to 22 carbon atoms, phenyl group, or alkyl phenyl group (the alkyl group in the alkyl phenyl group having 1 to 22 carbon atoms), and s is an integer of 1 to 300)
HOxe2x80x94R11xe2x80x83xe2x80x83(7)
(where, R11 represents alkyl group having 1 to 22 carbon atoms, phenyl group, or alkyl phenyl group (the alkyl group in the alkyl phenyl group having 1 to 22 carbon atoms))
Furthermore, the present invention is achieved by
(6) a method for producing a polycarboxylic acid for a cement dispersant as shown in (3), (4) or (5) above, characterized in that the addition reaction of the alkylene oxide is conducted in the presence of a base catalyst.
Furthermore, the present invention is achieved by
(7) a cement dispersant comprising a polycarboxylic acid for cement dispersant obtained by the method as shown in (3), (4), (5) or (6) above.
Furthermore, the present invention is achieved by
(8) a cement composition comprising at least water, a cement and a cement dispersant, characterized in that as the cement dispersant the cement composition comprises the cement dispersant as shown in (1), (2) or (7) above.